Mechanism for controlling the pitch of propeller blades

ABSTRACT

A mechanism is disclosed for controlling the pitch of propeller or propeller blades, particularly for use in marine craft. The mechanism embodies the use of a pitch adjusting nut, cams or cam slots, and levers, so arranged as to produce maximum torque for adjusting the pitch of the blades, while requiring a minimal movement of the parts of the mechanism.

United States Patent 11 1 1111 3,912,417

Herbert 1 1 Oct. 14, 1975 [54] MECHANISM FOR CONTROLLING THE 3,331,446 7/1967 Feroy 416/167 x PITCH 0F PROPELLER BLADES 3,393,749 7/ 1968 Feroy 416/ 167 X 3,645,644 2/1972 Schwisow 416/167 X [76] Inventor: William B. Herbert, 111 Yantacaw Brook Road upperxMontclair NJ FOREIGN PATENTS OR APPLICATIONS 07043 585,673 10/1959 Canada 416/167 1,135,402 4/1957 France 416/244 [22] Flledi 15, 1974- 821,824 10/1959 United Kingdom... 416/167 NO: 822,469 10/1959 United Kingdom 416/165 Primary Examiner-Everette A. Powell, Jr. {211 11531 "iii .1711 7141 3231 2133 Age", or M4816 and omstei" [58] Field of Search 416/165, 16 M, 168

ABSTRACT References Cited A mechanism is disclosed for controlling the pitch of UNITED STATES PATENTS propeller or propeller blades, particularly for use in 1,293,884 2/1919 Nilsson 416/167 mafl'ne Craft The mechanism embodies the use of 1,832,075 11 1931 Wilson 416/167 pitch j ng m or Cam slots, and e so 2,472,836 6/1949 Kennedy et al.. 416/167 arranged as to produce maximum torque for adjusting 2,548,045 4/1951 Nichols 416/167 the pitch of the blades, while requiring a minimal NiChOIS movement of the parts of the mechanism 2,763,329 9/1956 Feroy 416/167 2,954,830 10/1960 Gehres.. 416/167 12 Claims, 8 Drawing Figures Sheet 1 of5 US. Patent Oct. 14, 1975 U.S. Patent Oct. 14, 1975 Sheet 2 of5 3,912,417

US. Patent Oct. 14, 1975 Sheet 3 of5 3,912,417

U.S.- Patent Oct. 14, 1975 Sheet 5 of5 3,912,417

44 I 38 v 40 40 47 I 39 2 24 227 4| 1 2| 43 45 l8 I7 3 a? I9 47 47 Zgg 24 4| Fig. 7

MECHANISM FOR CONTROLLING THE PITCH OF PROPELLER BLADES This invention relates, as indicated, to' a mechanism for controlling the pitch of propeller blades, but has reference more particularly to a mechanism which is especially adapted for use in marine craft.

A primary object of the invention is to provide a mechanism of the character described, comprising a pitch adjusting nut, cams or cam slots, and levers, so arranged as to be capable of providing a maximum of torque for rotating the blades, with minimal movement of said parts.

Another object of the invention is to provide a mechanism of the character described, which is capable of eliminating or minimizing backlash or flutter of the propeller blades about their axes.

A further object of the invention is to provide a mechanism of the character described, wherein greater contact area or bearing surface is utilized to rotate the blades than is obtainable in existing or prior art mechanisms used for this purpose.

A still further object of the invention is to provide a mechanism of the character described, which requires a minimum number of easily assembled parts of relatively simple construction, enabling the mechanism to be manufactured and sold at a reasonable price.

Other objects and advantages of my invention will become apparent during the course of the following description.

In the accompanying drawings forming apart of this specification, and in which like numerals are employed to designate like parts throughout the same.

FIG. 1 is a fragmentary schematic or diagrammatic view showing a controllable pitch propeller system, embodying the invention;

FIG. 2 is a view, partly in elevation and partly in section, showing a controllable pitch propeller and a portion of the operating mechanism therefor;

FIG. 3 is a longitudinal cross-sectional view, on an enlarged scale, of the propeller, taken on the line 3-3 of FIG. 4;

FIG. 4 is a cross-sectional view, taken on the line 44 of FIG. 3; 9

FIG. 5 is a cross-sectional view, taken on the line 55 of FIG. 3;

FIG. 6 is a cross-sectional view, taken on the line 6-6 of FIG. 3;

FIG. 7 is a cross-sectional view, taken on the line 7-7 of FIG. 3, and

FIG. 8 is a view, partly in elevation, and partly in section, of the end of the propeller opposite from the drive shaft.

Referring more particularly to the drawings and especially to FIG. 1, there is illustrated, in somewhat diagrammatic or schematic fashion, the aft portion 10 of a boat, a propeller 11, a propeller drive shaft 12, a V- drive 13 for the propeller shaft, an engine 14, a double differential device 15 for controlling the pitch of the blades of the propeller 11, and means 15a for indicating the position of the propeller blades and for activating the control mechanism.

The device 15 and means 15a are disclosed, in detail, in my U.S. Pat. No. 3,795,463, dated Mar. 5, 1974, and form the subject matter of a divisional application, Ser. No. 436,922, filed Jan. 25, 1974, carved out of said patent. It is to be understood, however, that the subject of the present application is not confined to use only with the device 15 and means 15a, but may be used in conjunction with other propeller driving mechanisnisi I propeller "11 comprises a tubular hub 16 having a cylindrical outer surface 17 and an axial cavity or bore defined, in part, by flat surfaces of sides 18, 19 and 20 (see FIG..7), a diametric cross-section through this cavity 'or bore being substantially in the form of an equilateral triangle. It is to be understood, in this connection, that the number of surfaces defining this axial cavity or bore will correspond to the number of propeller blades of the propeller, which, in this instance, is a three-bladed propeller. Thus, in a four-bladed propeller, the number of surfaces or sides would be four; in a five-bladed propeller, the number of surfaces or sides would be five. In a two-bladed propeller, the cavity would be square or rectangular in cross-section.

Extending through the wall of the hub 16, radially outwardly from the surfaces 18, 19 and 20, are circumferentially spaced bores 21, 22 and 23 (see FIG. 7), these bores having annular grooves or recesses 24 of V-shaped cross-section in the walls thereof adjacent their radially outer ends, for a purpose to be presently described.

The number of such radial bores, shown in this instance, corresponds with the number of propeller blades, so that it is to be understood that the number of bores is not limited in respect to this invention.

Secured to the rear end of the hub 16, as by means of socket head screws 25, is a conical cap 26 (see FIGS. 1, 2 and 8).

The hub 16, in turn, is secured as by means of socket head screws 27, to the driven section 28 (see FIG. 2) of the hollow or tubular propeller shaft 12.

The driven section 28 of the propeller shaft is connected, as by screws 29, to a collar 30, which is connected, as by screws 31, to a second collar 32. The collar 32 is connected, as by screws 33, to a tubular output shaft 34, which is coupled to the output shaft of the V- drive 13. The manner in which the shaft 34 is mounted and driven is disclosed in my aforesaid U.S. Pat. No. 3,795,463, and need not be further explained.

- The propeller, in this case, comprises three circumferentially' spaced blades 35, 36 and 37 of identical construction.

Each blade is, as best seen in FIG. 7, secured, as by means of four circumferentially spaced cap screws 38, to a conical blade base 39-disposed in the outer end of the bore 21, 22 or 23. The blade base is provided with circumferentially spaced unthreaded openings 40 for passage therethrough of the screws 38. The screws 38 are threadedly secured to an annular blade root 41 disposed in the inner end of the bore 21, 22 or 23, and having a conical portion 42. The blade root 41-42 is provided with threaded openings 43 for receiving the ends of the screws 38.

For the purpose of securing the blade base 39 to the blade root 41-42, prior to the attachment of the blade root, a socket head screw 44 is provided, which extends through an unthreaded central opening 45 in the blade base 39 and is threaded into a threaded opening 46 of the blade root.

I The blade base 39 and conical portion 42 of the blade root 41 respectively coact with the annular grooves or recesses 24 to confine therebetween a'bearing consisting, in this instance, of bearing rollers 47.

Ball bearings or other types of bearings may be used, instead of bearing rollers.

The aforesaid method of connecting the blades to the blade roots, and the advantages thereof, are disclosed and claimed in my aforesaid US. Pat. No. 3,795,463, but a portion of such description is repeated herein, as a basis for disclosure of the pitch control mechanism, which is the principal feature of the present application, and will now be described.

Mounted for slidable axial movement in the axial cavity or bore of the hub 16 is a nut 48 controlling or adjusting the pitch of the propeller blades.

The nut 48 is of triangular shape conforming in contour to the axial cavity or bore of hub 16, and having a threaded axial bore extending therethrough.

A portion of the nut 48, designated by reference numeral 48a, and disposed in closely spaced relation to one end of the nut, as seen in FIG. 3, is of the same triangular conformation, as the nut, but of smaller crosssection, whereby to provide slots 49, 50 and 51 in the nut, for a purpose to be presently described.

Portions of the axial cavity or bore of the hub 16, to which reference has been made, are provided with recesses 52, 53 and 54 (see FIGS. 3, 4 and 5) which are adapted to have received and secured therein cam plates 55. Each of these cam plates 55 is provided in its inner face with a closed-end cam slot 56, which extends diagonally across the plate, as in FIG. 4.

Portions of the axial cavity or bore of the hub 16 are also provided with recesses 57, 58 and 59 (see FIGS. 3, 4 and 6) which are adapted to have received and secured therein cam plates 60. Each of these cam plates 60 is provided in its inner face with a closed-end cam slot 61, of curved contour, as in FIG. 4.

Interposed between the outer faces of the pitch adjusting nut 48 and the faces of the axial cavity or bore of the hub 16 are levers 62 of arcuate shape, as best seen in FIG. 4. Each of these levers extends through an arcuate slot 63 in the inner end (see FIGS. 3, 4 and 7) of the blade root 41.

Each lever 62 is provided at one end with a pin 64, which extends transversely through the lever and is provided at its outer end with a cam roller 65, and at its inner end with a cam roller 66. The rollers 65 are movable in the cam slots 56 of the cam plates 55, and the rollers 66 are movable in the cam slots 49, 50 or 51 of the nut 48.

Each lever 62 is provided at its other end with a pin 67, which extends transversely through the lever and is provided at its outer end with a cam roller 68. The rol- Iers 68 are movable in the cam slots 61 of the cam plates 60.

For the purpose of moving the nut 48 longitudinally through the hub 16, to control the pitch of the propeller blades, a control screw 69 is provided, the threads of which are in threaded engagement with the threaded bore of the nut 48.

The control screw 69 is keyed to a coupling member 70, which is interlocked with a coupling member 71. This coupling may, for example, be a Boston coupling No. FCBBIS.

The coupling member 71 is secured to the after end of a control shaft 72, which is mounted for rotation in radial thrust bearings 73 and 74 mounted in the driven section 28 of the propeller shaft. The bearing 73 is retained against axial displacement relatively to the driven section 28 by means of a snap ring 75 secured to the shaft 72 adjacent the bearing 73. Forwardly of the bearing 74, the shaft is of reduced diameter, this portion being designated by reference numeral 72a, and referred to as the control shaft. The control shaft 72a extends axially through the output shaft 28 and into the differential device 15, to which reference has previously been made.

The control screw 69 has loosely mounted thereon a collar of the conformation shown in FIG. 6, and which is caused to bear resiliently against the levers 62 by means of a compression coil spring 81, which is interposed between the collar 80 and a second collar 82, which is also loosely mounted on the screw 69. The collar 82 bears against a retainer 83 (FIGS. 3 and 8), which is mounted in the cap 26 of the propeller.

The pressure of the collar 80 against the levers 62 serves to maintain a preload between the cam rollers 65 and 66 and the slots in which these rollers are disposed, and to prevent looseness between the operative parts of the pitch control mechanism.

Since greater force is required to rotate the propeller blades in one direction than in the other, that is to say, ahead forward pitch adjustment requires greater force in normal operation than aft or rearward adjustment. The compression of the spring 81 will occur when the torque requirement is not at a maximum, and the decompression or extension of the spring will lessen the torque required when turning the blades into forward pitch, in addition to preventing back lash or looseness in the mechanism.

The control screw 69 is journalled in a radial bearing 84 (see FIGS. 3 and 8) secured within the cap 26 by the retainer 83.

A forward and reverse thrust bearing for the screw 69 is also provided within the cap 26, and consists of thrust plates 85 and 86 and a spacer ring 87. The plates 85 and 86 having confronting faces provided with annular ball tracks to accommodate balls 88, while a bearing disc 89 is keyed or fixed to the screw 69, and is also provided with annular ball tracks to accommodate the balls 88. The balls 88 between the plate 86 and disc 89 are for taking the thrust in one direction of the screw 69, while the balls 88 between the plate 85 and disc 89 are for taking the thrust of the screw in the opposite direction. The spacer ring 87 determines the preload on these ball thrust bearings.

METHOD OF OPERATION The method of operation, or method of controlling or adjusting the pitch of the propeller blades may be briefly described as follows:

When the control screw 69 is rotated in one direction, as, for example, in a direction to cause movement of the pitch adjusting nut 48 from the position shown in FIG. 3 to the right of such position, the cam rollers 66 will be caused by the nut to move to the right, thereby causing the cam rollers 65 to traverse the slots 56 in the cam plates 55, while, at the same time, the cam rollers 68 will be caused to traverse the slots 61 in the cam plates 60.

This movement of the cam rollers 65 and 68 causes the levers 62 to be moved from the position shown in solid lines in FIG. 4 to the position shown in broken lines. In the course of this movement, the levers 62 slide through the slots 63 in the blade roots 41, causing the blade roots 41 to rotate about their axes, and the propeller blades to be likewise rotated. This rotative movement is a resultant of the axial movement of the pitch adjusting nut and the lateral movement of the levers 62 caused by the cam slots 56 and 61.

When the control screw 69 is rotated in the opposite direction, the pitch adjusting nut 48 will be moved toward the left and the levers 62 from the aforesaid broken line position to the solid line position, causing the blade roots 41 to rotate about their axes, and the propeller blades likewise rotated, but in a direction opposite to that described above.

The advantages of this cam and lever pitch adjusting mechanism may be briefly described as follows.

When the ends of the levers 62 which carry the rollers 65 and 66 are extended to the maximum distance from the axes of the blade roots 41, the torque or leverage capable of being applied to rotate the propeller blades is at a maximum, and, conversely, when the same ends of the levers are closest to the axes of the blade roots, the maximum amount or degree of blade rotation is obtained from a minimum movement of the pitch adjusting nut. This principle, which may be termed variable ratio, provides a mechanism which is so arranged that maximum torque is available when required, as, for example, when full ahead position of the blade pitch is desired.

The mechanism minimizes or eliminates back lash or flutter of the blades about their axes. This advantage results from the increased radius or distance from the center line of the blade axis to the points at which the rollers 65 and 66 engage their cam slots.

The levers 62 having a curvature or are which matches or conforms to the curvature or arc of the slots 63 in the blade roots 41 provide more contact bearing to rotate the blade roots than is obtainable by the use of pins 60 and 61 in my aforesaid patent 3,795,463, or through use of the mechanisms disclosed in U.S. Pat. Nos. 1,396,325 and 2,711,796, and British Pat. Nos. 822,469 and 860,205. This additional contact, when combined with the increased radius at which force is applied by the slot 49, 50 and 51 in pitch adjusting nut 48 and cam slots 56 in cam plates 52 of the present mechanism, provide greater rigidity and force of motion, combined with greater resistance to rotational movement of the propeller blades from thrust, hydrodynamic, centrifugal or other external forces.

A further advantage resides in the simplicity of construction of the mechanism described, requiring a minimum number of easily assembled parts of relatively simple construction, enabling the mechanism to be manufactured and sold at a reasonable price.

Although the levers 62 and slots 63 are described as being of arcuate shape or configuration, it may be noted that straight levers and slots may be used, but are not as effective as the arcuate levers and slots.

It is to be understood that the form of my invention, herewith shown and described, is to be taken as a preferred example of the same, and that various changes may be made in the shape, size and arrangement of parts thereof, without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. In a controllable pitch propeller, a hub having an axial bore, a plurality of circumferentially-spaced bores extending from said axial bore through said hub and having their axes radial to said hub, propeller blades mounted in said radial bores and having blade roots adjacent the radially innermost ends of said radial bores,

said blade roots having slots in their inner ends, pitch adjusting means within said axial bore, said means comprising a control screw, a nut movable axially of said axial bore by said screw, cam and lever means responsive to movement of said nut, for rotating said blades about their axes, said cam and lever means comprising levers movable substantially longitudinally in said blade root slots, and cam slots in fixed relation to said hub and effective upon longitudinal movement of said levers to cause the ends of the levers to traverse said cam slots and impart a rotative movement to the levers.

2. A controllable pitch propeller, as defined in claim 1, wherein said blade root slots are arcuate-shaped, said levers are arcuate-shaped to conform with the arcuate shape of said blade root slots, whereby said levers are slidable in said blade root slots, and cam plates are provided which are secured to said hub and have said cam slots therein.

3. In a controllable pitch propeller, a hub having an axial bore, a plurality of circumferentially spaced bores extending from said axial bore through said hub, and having their axes radial to said hub, propeller blades mounted in said radial bores and having blade roots adjacent the radially innermost ends of said radial bores, said blade roots having arcuate slots therein, and pitch adjusting means within said axial bore, said means comprising a control screw, a nut movable axially of said axial bore by said screw, and cam and lever means responsive to movement of said nut, for rotating said blade roots about their axes, said cam and lever means comprising arcuate levers slidable in said blade root slots, and cams having slots therein for imparting a lateral movement to said levers in the course of said slidable movement thereof, said levers being provided at one end with cam rollers, and said nut being provided with slots or recesses in which said cam rollers are guided.

4. A controllable pitch propeller, as defined in claim 3, wherein means are provided in said axial bore for resiliently biasing said levers in one direction.

5. A controllable pitch propeller, as defined in claim 4, including thrust bearing means for said control screw.

6. In a controllable pitch propeller of the character described, a hub having an axial bore, a plurality of circumferentially spaced bores extending from said axial bore through said hub and having their axes radial to said hub, propeller blades mounted in said radial bores for pitch adjustment about the axes of said radial bores, said blades having slots in their inner ends, means for adjusting the pitch of said blades, said means comprising a control screw extending axially of said hub, a nut movable axially of said axial bore by said screw, cam and lever means responsive to movement of said nut for rotating said blades about the axes of said radial bores, said cam and lever means comprising levers movable substantially longitudinally in said slots, and cam slots in fixed relation to said hub and effective upon longitudinal movement of said levers to cause the ends of the levers to traverse said cam slots and impart a lateral movement to the ends of said levers concurrently with said longitudinal movement.

7. A controllable pitch propeller, as defined in claim 6, wherein said first-named slots are arcuate-shaped, said levers are elongated levers of curvature identical with that of said arcuate slots and slidable in said arcuate slots, and cam plates are provided which are secured to said hub and have said cam slots therein.

8. In a controllable pitch propeller, of the character described, a hub having an axial bore, a plurality of circumferentially spaced bores extending from said axial bore through said hub and having their axes radial to said hub, propeller blades mounted in said radial bores for pitch adjustment about the axes of said radial bores, said blades having arcuate slots therein, and means for adjusting the pitch of said blades, said means comprising a control screw extending axially of said hub, a nut movable axially of said axial bore by said screw, and cam and lever means responsive to movement of said nut, for rotating said blades about the axes of said radial bores, said cam and lever means comprising elongated levers of curvature identical with that of said arcuate slots, and slidable in said slots, and cams having cam slots therein for imparting a lateral movement to said levers concurrently with said slidable movement, said levers being provided at one end with cam rollers, and said nut being provided with slots or recesses in which said cam rollers are guided.

9. A controllable pitch propeller, as defined in claim 8, wherein means are provided in said axial bore for resiliently biasing said levers in one direction.

10. A controllable pitch propeller, as defined in claim 9, including thrust bearing means for said control screw.

1 l. A controllable pitch propeller, as defined in claim 2, wherein said levers are provided at their ends with elements which are movable in said cam slots.

12. A controllable pitch propeller, as defined in claim 7, wherein said levers are provided at their ends with elements which are movable in said cam slots. 

1. In a controllable pitch propeller, a hub having an axial bore, a plurality of circumferentially-spaced bores extending from said axial bore through said hub and having their axes radial to said hub, propeller blades mounted in said radial bores and having blade roots adjacent the radially innermost ends of said radial bores, said blade roots having slots in their inner ends, pitch adjusting means within said axial bore, said means comprising a control screw, a nut movable axially of said axial bore by said screw, cam and lever means responsive to movement of said nut, for rotating said blades about their axes, said cam and lever means comprising levers movable substantially longitudinally in said blade root slots, and cam slots in fixed relation to said hub and effective upon longitudinal movement of said levers to cause the ends of the levers to traverse said cam slots and impart a rotative movement to the levers.
 2. A controllable pitch propeller, as defined in claim 1, wherein said blade root slots are arcuate-shaped, said levers are arcuate-shaped to conform with the arcuate shape of said blade root slots, whereby said levers are slidable in said blade root slots, and cam plates are provided which are secured to said hub and have said cam slots therein.
 3. In a controllable pitch propeller, a hub having an axial bore, a plurality of circumferentially spaced bores extending from said axial bore through said hub, and having their axes radial to said hub, propeller blades mounted in said radial bores and having blade roots adjacent the radially innermost ends of said radial bores, said blade roots having arcuate slots therein, and pitch adjusting means within said axial bore, said means comprising a control screw, a nut movable axially of said axial bore by said screw, and cam and lever means responsive to movement of said nut, for rotating said blade roots about their axes, said cam and lever means comprising arcuate levers slidable in said blade root slots, and cams having slots therein for imparting a lateral movement to said levers in the course of said slidable movement thereof, said levers being provided at one end with cam rollers, and said nut being provided with slots or recesses in which said cam rollers are guided.
 4. A controllable pitch propeller, as defined in claim 3, wherein means are pRovided in said axial bore for resiliently biasing said levers in one direction.
 5. A controllable pitch propeller, as defined in claim 4, including thrust bearing means for said control screw.
 6. In a controllable pitch propeller of the character described, a hub having an axial bore, a plurality of circumferentially spaced bores extending from said axial bore through said hub and having their axes radial to said hub, propeller blades mounted in said radial bores for pitch adjustment about the axes of said radial bores, said blades having slots in their inner ends, means for adjusting the pitch of said blades, said means comprising a control screw extending axially of said hub, a nut movable axially of said axial bore by said screw, cam and lever means responsive to movement of said nut for rotating said blades about the axes of said radial bores, said cam and lever means comprising levers movable substantially longitudinally in said slots, and cam slots in fixed relation to said hub and effective upon longitudinal movement of said levers to cause the ends of the levers to traverse said cam slots and impart a lateral movement to the ends of said levers concurrently with said longitudinal movement.
 7. A controllable pitch propeller, as defined in claim 6, wherein said first-named slots are arcuate-shaped, said levers are elongated levers of curvature identical with that of said arcuate slots and slidable in said arcuate slots, and cam plates are provided which are secured to said hub and have said cam slots therein.
 8. In a controllable pitch propeller, of the character described, a hub having an axial bore, a plurality of circumferentially spaced bores extending from said axial bore through said hub and having their axes radial to said hub, propeller blades mounted in said radial bores for pitch adjustment about the axes of said radial bores, said blades having arcuate slots therein, and means for adjusting the pitch of said blades, said means comprising a control screw extending axially of said hub, a nut movable axially of said axial bore by said screw, and cam and lever means responsive to movement of said nut, for rotating said blades about the axes of said radial bores, said cam and lever means comprising elongated levers of curvature identical with that of said arcuate slots, and slidable in said slots, and cams having cam slots therein for imparting a lateral movement to said levers concurrently with said slidable movement, said levers being provided at one end with cam rollers, and said nut being provided with slots or recesses in which said cam rollers are guided.
 9. A controllable pitch propeller, as defined in claim 8, wherein means are provided in said axial bore for resiliently biasing said levers in one direction.
 10. A controllable pitch propeller, as defined in claim 9, including thrust bearing means for said control screw.
 11. A controllable pitch propeller, as defined in claim 2, wherein said levers are provided at their ends with elements which are movable in said cam slots.
 12. A controllable pitch propeller, as defined in claim 7, wherein said levers are provided at their ends with elements which are movable in said cam slots. 